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Posted: August 21, 2006

Study tracks magnetic nanoparticles targeting breast tumors

(Nanowerk News) An in-depth study of nanoparticle distribution in tumor-bearing mice has shown that targeted magnetic nanoparticles accumulate and cluster in both primary breast tumors and metastatic lesions that have developed in the lung. These results suggest that targeted magnetic nanoparticles should be useful in both detecting and treating metastatic breast cancer.

Reporting its work in the journal Materials Science and Engineering C ("A TEM study of functionalized magnetic nanoparticles targeting breast cancer cells"), a team of investigators led by Winston Soboyejo, Ph.D., at Princeton University, used transmission electron microscopy (TEM) to study tissue and cellular distribution of iron oxide nanoparticles targeted to breast tumors. As a targeting agent, the researchers used a peptide known as luteinizing hormone-releasing hormone (LHRH), a naturally occurring hormone that stimulates the production of sex hormones in both females and males. Breast cancer cells commonly overproduce a cell-surface receptor for this hormone.

The investigators conducted their studies by first injecting LHRH-tagged iron oxide nanoparticles into mice with human breast tumors. Twenty hours later, the researchers used TEM to examine the tumors, lungs and other organs from the mice. Individual nanoparticles and nanoparticle clusters were readily visible inside tumor cells, as well as in liver cells. In tumor cells, iron oxide nanoparticles clustered at the cell membrane, while in liver cells the particles accumulated within the nucleus. The researchers found no nanoparticles in kidney cells.

A finding that surprised the investigators was that they observed large numbers of nanoparticles in the lungs of animals in which tumors had been growing for 30 days. Following up on this observation, the researchers found that the number of iron oxide particles in the lung correlated with the number of metastatic cells present in lung. From this discovery, the researchers concluded that LHRH-targeted magnetic iron oxide nanoparticles may be useful for detecting breast cancer in its earliest stages as well as for spotting metastatic lesions in the lung.